Stretching press



June 17, 1941.

J. SALZMANN STRETGHING PRESS Filed April l, 1939 3 Sheets-Shea?I 1 4Inventor.'

AfrlllNly nel' `fune 17, 1941.

J. sALzMANN STRETCHING PRESS Filed April l, 1939 3 Sheets-Sheet 2 June17, 1941. J. sALzMANN 2,245,723

STRETCHING PRESS Filed April l, 1939 3 Sheets-Sheet` 3 /n venor @luf/x.S4( @Mv KWS. i

IIIIIII gr gite- 1. .russia-.1941

STRETCHING PRESS Josef Salzmann, Munich, Germany, assignor to HenschelFlugzeug-Werke A. G., Schoenefeld,

Kreis Teltow, Germany Application April l, 1939, Serial No. 265,428

In Germany April'7, 1938 7 Claims.

'Ihe present invention relates to a stretching press with which a sheetmetal clamped in opposed vises may be shaped by a die secured to adie-table. In machines of the type under consideration the shapingoperation is carried through by raising the table and die with the aidof plungers actuated by a pressure means and thus pressing the dieagainst the surface of the sheet metal held by the vises in operativeposition. During the shaping operation it occurs frequently that thestresses created in the sheet metal by the tensile forces acting in thedirec.- tion of the opposite vises fail to cause certain individualportions of the sheet metal to follow the contours of the die. If suchportions are small, they are usually worked with hand hammers-during thestretching operation. If, however, such portions are larger the sheetmetal is reclamped in another position and thus stretched in thepertainingdirection. Stretching presses are already known in the art,which are equipped with a square die table and with vises for the sheetmetal, opposite the four sides of the table for the purpose of clampingthe sheet metal on all sides or of using either the one or the otherpair of opposite vises.

The present invention aims to improve a die press of the said type so asto simplifyand to reduce the cost of the operations of stretching thejob in two directions at r..ght angles to each other. A further objectof the invention is to make the die press useful for the production ofelongated as well as of deep forms.

'Ihe invention mainly comprises a stretching machine with a die tablewhich is rotatable about a vertical axis .and adjustable in variouspositions for operation between two opposite vises. The inventionfurther consists of vises adjustable to an extent corresponding to thedifference of the diametral dimensions of the die table surface.

According to the invention the stretching press is preferably sodesigned that the die table is pivoted with a central journal about avertical axis and shiftable in the direction of such axis, a pluralityof plungers being diametrically arranged on a circle, and the plungerheads being adapted to serve as supports of the die table.

Further details and objects of the invention will be apparent from thedescription hereinafter and the accompanying drawings showing anembodiment of the invention by way of example.

In the drawings:

Fig. l is a top plan view of a device according to the invention Fig. 2is aside elevation of the device ofFig. 1 gartially a sectional viewalong 'the line II-II of Fig. 3 is a side elevation similar to that ofFig. 2 the die table being turned Fig. 4 is a top view corresponding toFig. 3;

Fig. 5 is a transverse sectional. view along the line V-V of Fig. 3 inan enlarged scale, the pressing plungers being in their lowermostinoperative position to facilitate the turning of the die table;

Fig. 6 is a top view of the device shown in the preceding figures, thedie table being replacedby another-of a modified form.

Referring now to the drawings, there is a frame comprising two spacedlongitudinal members I connected tov each other by end members 2 and across-member 3. A central bearing 4 with vertical axis is provided inthat cross member for a king-pin-like journal,5 of a die table 6, whichthus, is rotatable about said vertical bearing axis. The die table isadapted to receive thereon a die l, which may be secured to the table byany suitable means, such as indicated at 32. Laterally of said die tableand opposite to each other two vises or groups of vise devices 8 and 9are arranged on said longitudinalmembers so as to be movable thereontowards and away from said die table. .Each of the vises 8 and 9 isprovided with a lower projectiony I0 and II respectively serving as ameans of connection for a drive to shift the vises in the saiddirections. In the illustrated embodiment, such drives comprise spindlesI2 and I3 respectively engaging interior threads I4 and I5 ofthepertaining projections I0 and II. The spindles I2 and I3 are supportedin bearings' I6 and II respectively provided in the end members 2 and inthe cross member 3. In order to rotate the spindles and to shift therebythe vises, the spindles maybe connected to electric motors I 8 and I9respectively. The vises may be provided with clamp plates 20 and'screwbolts 2l to secure them in an adjusted position. On a circle 22 aboutthe axis ofthe king-pin 5 pairs of lifting devices such as plungers areso arranged that the individual plungers of a pair are diametricallyopposite each other. In the illustrated embodiment', twopairs 23 and 24of plungers are provided.

l However, any desired number of pairs may be used. Each plunger deviceis connected to av pipe line indicated at 25 for admitting anddischarging a pressure means whereby a plunger may be raised andlowered. The plungers have heads 2G and 21 respectively, adapted to bearfrom below against supporting surfaces 28 of the die table 6.

Suitable means may be provided for rotating the die'table 6. Such meansmay comprise a worm drive 29, which may be connected to an actuatingmeans such as electric motor 30. Worm 29 engages a gear wheel 3l whichis secured to king-pin so as to be capable of rotating the latterwithout interfering with an axial movement of the kingpin relatively towheel 3|.

Now, in order to produce elongated forms, first all plungers 23 and 24are lowered to their lowermost position. Shortly before those plungers,which are just carrying the die table, reach that position, the lowercenter surface 33 of the die table abuts against the top surface ofbearing 4 so that the die table is borne by the latter as shown in Fig.5. Then, the die table may be adjusted to the position illustrated inFigs. 1 and 2 by actuation of the worm drive device 29, 30, 3i.Thereupon, the die 1 may be secured to the table 6 and a metal sheet 36spread over the die. By turning the spindles I2 and I3, the vises may bebrought into correct position so as to receive and clamp opposite edges34 of the metal sheet. By tightening the screw bolts 2l', the vises willi be safely held in their adjusted position. 'I'hereafter, a pressuremeans may be admitted to pair of plungers 24. In rising, the heads 26 ofplungers 24 will contact the surfaces 23 and then lift and press the dietable with the die against the lower surface of the metal sheet, therebystretching the latter and shaping it according to the form of the die.-In order now to perform stretching of the sheet metal 36 in a directionat right angles to the first stretching operation, the edges 34 of thesheet metal will be released from the vises, and the plungers 24 lowereduntil they have deposited the die table withsurface 33 on the top ofbearing 4. Thereafter, the table may be turned 90 degrees in the ma'nnerhereinbefore described, so as-to take the position illustrated in Figs.3, 4 and 5. Then the vises will be shifted close to the table so as togrip the edges 35 of the sheet metal 36. After the edges 35V are securedto the vices, the plungers 23 may be actuated to cause the stretching ofthe sheet in a direction at right angles to the first stretching.

Thus the die press according to the present invention is useful to applyelongated and narrow dies to long jobs which are to be stretched in thelongitudinal direction of the die, when the die table is positioned withits longitudinal extension between the vices. Or, dies for jobs of adeep form may be used which jobs are to be stretched transversely of thedie when the table is turned 90 degrees off the first mentionedposition, and the `vises are shifted close to the table. Furthermore,with jobs which' are to be stretched in different directions it ispossible by turning the table, to reclamp the job without removing itfrom the die.

Fig. 6 shows a die table 4U which is a modification of that of Figs. 1to 5. The die table 40 is of a substantially square shape and has ajournal 4I `and alower ring-shaped supporting surface 42 adapted to beengaged by all plungers 23 and 24. It is clear, that with a so shapeddie table, the plungers may be actuated either'in pairs as describedhereinbefore, or all at once. Furthermore the turning of the table andthe reclamping of the job may take place without rst lowering the tableto a position where it may be supported by a stationary abutment such assurface 33 in cooperation with bearing 4 of Figs. 1 to 5. In otherrespects the die press of Fig. 6 is similar to that shown in thepreceding figures. The table design of Fig.'6 is particularly adapted tofacilitate repeated reclamping and stretching in different directions.

Other suitable forms of the die table and of the arrangement of devicesfor lifting the same, and which are within the scope of my inventionwill be apparent to those skilled in the art.

What I claim, is:

1. A die press comprising in combination two opposite vises movabletowards and away from each other in a horizontal path, a die tablearranged between said vises and including a kingpin with vertical axis,a collar bearing for said king-pin, two pairs of diametrically oppositedevices for lifting and lowering said die table, said devices beingarranged on a circle about said vertical axis and one of said pairs onthe circle diameter which coincides with the direction of the path ofthe vises, and the other one of said pairs on a diameter at right anglesto that of the first mentioned pair, and means for adjusting said visesas to their distances from said vertical axis.

2. A die press comprising in combination two opposite vises movabletowards and away from each other in a horizontal path, a die tablearranged between saidvises and adapted to rotate through at least abouta vertical axis, means for lifting and lowering said die table, anabutment for said die table to support it in its lowermost position,said abutment being so arranged and constructed as to permit rotation ofsaid die table when bearing on said abutment, and means for adjustingsaid vises as to their distances from said vertical axis, said means forlifting and lowering said die table comprising two pairs of plungersarranged on a circle about said vertical axis, the plungers of one ofsaid pairs being arranged on that diameter which coincides with thedirection of the path of said vises, and the plungers of the other pairbeing arranged on a diameter at right anglesto the first mentioneddiameter, said plun'gers including heads adapted to engage said dietable from below, and having a lowest position in which said heads donot engage said die table when the latter is ih its lowermost position.

3. A die press comprising in combination two opposite vises movabletowards and away from each other in a horizontal path, a die tableincluding a lower center pin with vertical axis and being rotatablethrough not less than 90 about said vertical axis, a collar bearing forsaid pin, so arranged and constructed as to permit rotation and axialdisplacement of said pin with said table relatively to said bearing, aplurality of diametrically opposite plungers arranged on a circle aboutsaid vertical axis, each of said plungers including `a head adapted tosupport said die table, and a ring-shaped surface on the bottom side ofthe tablefor engagement with said plunger head.

4. A die press comprising in combination two opposite vises movabletowards and away from each other in a horizontal path, a dietablearranged between said vises and rotatable through at least an angleof 90 about a vertical axis, and a plurality of pairs of devices forlifting and lowering said die table, the individuals of each pair beingarranged diametrically opposite withfreL.;

antenas clding a king pin aiid heilig ariaiised between said vises androtatable about the axis of said king pin through at least an angle of90. splu- 'raiity of pairs of devices for lifting and lowering said dietable, the individuals of each pair being arranged diametricallyopposite with respect to said axis and being spaced to support the tablein predetermined angular positions. and means in a driving connectionwith said king pin for rotating said die table.

6. A die press as claimed in claim 4 further comprising an abutment forsaid die table to support it in a lowermost position when said devicesin lowering said table have deposited it on said abutment, said abutmentbeing so constructed and arranged as to permit rotation of said dietable when bearing on said abutment.

'7. A die press comprising in combination two opposite vises movabletowards and away from of said pairs whereby lifting and lowering of.saidI die may be effected by either one of said pairs depending on theposition of said die table with said supporting faces opposite the oneor the other pair of said lifting and lowering devices, and means foradjusting said vises as to their distances from said vertical axis.

J OSEF SALZMANN.

